while digging around at my favorite parts yard i came across wheat appears to be a very clean(almost new looking) AFM on a 633. the part #'s are different, the one on the 633 ends in 016 . i'll have to check what the 635 ends in, but i know it's different. the guy at the shop could not tell me what the differences were, so i didn't take a $75 chance. a little high for what he usually charges me for parts, but i still thought that was a good price if in fact it is nearly new.

i tried using an 87 535i afm in my car (83 633) when trying to figure out my starting issue. When i got the car running, i tried it again and it would not idle very well at all, and would shutter when i hit the gas. It worked, but not smooth. I tihnk the problem is the air/fuel ratio or something. I know that a friend of mine got it to work pretty well after cracking the thing open and messing with it to get the right ratio, but it still isnt spot on. He put an 89 535 motor into his 733 and kept the same wiring harness and motronic system that the 3.2L had.

-Jeff

The 633 used the 016 AFM and the 635 used the 027 AFM which is found on the 535,635,735 in the e23/e24/e28/e32 and e34 chassis. I found one at the local pull-a-part that was a later one and was trying to decide if I should purchase it or not and decided to pass at about $20. I have spares and really did not need another one to just sit on the shelf. So $75 if you really need one might be okay but for a spare, it is awful steep.

i didn't really know i had a problem until driving the sons new 6. on my old AFM i adjusted the wiper to go on fresh substrate and it has always done well,so i thought. but it seemed kind of jerky on it's way up to 3k, and then it would just kick in. i thought it was just coming on cam. i've swapped ECU's(done the resolder of the pins)also in the past. then driving sons 6,it is smooth up to 3k and beyond,his obc indicates about 4 extra mpg as well. I do have 3 or 4 spares and i have just swapped in the best looking one,and it has smoothed out some climbing up to the 3k.
i just saw this new looking one in the 633 and was wondering. i could get him down a little,but i will pass. next time i go i will look at the all the correct ones. may be a good looking one in the bunch,because he does have 5's and 7's also. just don't go over there often due to 100 mile round trip. but it's always worth the drive.